It is known to use a laser beam for performing the operations of welding or cutting, for example, of flat work pieces such as sheet metal and the like. The quality of such welding or cutting operations by means of a laser beam depends on several factors which must be maintained constant to assure a consistently good quality of the operations being performed. For example, in connection with sheet metal it is critical that the spacing between two sheets of sheet metal remains constant relative to each other and that the spacing between the sheet metal work pieces to be welded and the laser head also remains constant to assure a uniform laser efficiency throughout the operation. A pressure roller has been used to control the just mentioned spacings.
The quality of the surface of the work pieces also has a substantial influence on a consistently high quality of the laser operation being performed. The surface condition of the work piece influences the welding or cutting operation by the laser beam because the degree of reflection and the degree of dispersion have an influence on the operation efficiency of the laser beam generated in a laser head.
It has also been found that a surface layer on the work piece, for example, in the form of contamination, in the form of oxide layers or in the form of protective coatings adversely influence the operation quality. Such adverse influences have been noted independently of the type of coating. In other words, metallic coatings and non-metallic coatings have an adverse influence on the efficiency of the laser operation because these coatings negatively influence the heat flow from the laser beam to the point where the laser beam performs its operation.
Another problem is caused by spattered particles generated by the laser beam action. Such particles must be kept away from the point where the beam is to be effective and they must also be kept away from the surface after the laser beam has been effective so that the work piece is suitable for further operations and use. The removal of these spattered particles requires respective operations upstream of the laser beam action and also downstream of the laser beam action as viewed in the direction of relative movement between the laser beam and the work piece. The several working operations have been performed heretofore on different machines requiring repeated handling of the work piece, which is not cost efficient.
Repeated handling of the work piece is time consuming and hence expensive. Additionally, such handling exposes the work piece to repeated contamination not only by deposition of dirt, but also by a new oxide formation on the surface of the work piece, thereby adversely affecting the laser operation.